Different methodologies have been implemented for the detection of EGFR mutations in the CTCs of NSCLC patients, such as the combination of CTC enrichment by the CellSearch (Menarini Silicon Biosystems, Inc., Bologna, Italy) system with next-generation sequencing (NGS), with sensitivity and specificity of 84% and 100%, respectively, corresponding to those present in tumor tissue [174]. The gene discussed is EGFR; the disease is neoplasm.